Freeman Dyson is a physicist who has been teaching at the Institute for Advanced Study in Princeton since Albert Einstein was there. When Einstein died in 1955, there was an opening for the title of "most brilliant physicist on the planet." Dyson has filled it

So when the global-warming movement came along, a lot of people wondered why he didn’t come along with it. The reason he’s a skeptic is simple, the 89-year-old Dyson said when I phoned him.

"I think any good scientist ought to be a skeptic," Dyson said.

Dyson came to this country from his native England at age 23 and immediately made major breakthroughs in quantum theory. After that he worked on a nuclear-powered rocket (see video below). Then in the late 1970s, he got involved with early research on climate change at the Institute for Energy Analysis in Oak Ridge, Tenn.

The justices of the United States Supreme Court this week became the world’s most august global warming sceptics. Not by virtue of their legal reasoning – the global warming case they decided turned on a technical legal issue — but in their surprising commentary. Global warming is by no means a settled issue, they made clear, suggesting it would be foolhardy to assume it was.

The court decision noted that the Environmental Protection Agency itself had “Acknowledg[ed] that not all scientists agreed on the causes and consequences of the rise in global temperatures,” before suggesting readers consult “views opposing” the conventional wisdom. Specifically, the justices’ recommended reading was a superb profile of Princeton’s Freeman Dyson, perhaps America’s most respected scientist, written in the New York Times Magazine, March 29, 2009.

Freeman, an unabashed skeptic, believes that carbon dioxide, rather than being harmful, is both necessary and desirable, arguing that “increases in atmospheric carbon dioxide produce many beneficial effects upon the natural plant and animal environments of the Earth.”

Somewhat in the same vein, Justice Ginsburg notes carbon dioxide is necessary and ubiquitous, and thus shouldn’t be the target of indiscriminate attacks. “After all, we each emit carbon dioxide merely by breathing,” she notes, repeating a point that Dyson couldn’t have said better himself.

To see exactly what the Supreme Court said in its remarkable American Electric Power v. Connecticut decision, click here.

As a climate scientist I am writing personally to you as the online editor to strongly object to the blocking of my comments regarding the conversation by your science editor Mr Connor with Professor Dyson. My comments sent last night were phrased in very reasonable and temperature language and highlighted the serious and very misleading mistakes given by Mr Connor.

It is simply wrongfor Mr Connor to say that present carbon dioxide levels are probably at their highest level for 800 000 years. In fact it is total nonsense. The Cambrian era had carbon levels 20 times what they are today and the Ordovician era which was mostly an ice age(yes an ice age!) had carbon dioxide levels 10 times todays level.( see the analysis by Professor C R Scotese Professor of Geology at the University of Texas www.scotese.com).

World-renowned physicist Professor Freeman Dyson has been described as a 'force-of-nature intellect'. He's also one of the world's foremost climate change sceptics. In this email exchange, our science editor, Steve Connor, asks the Princeton scholar why he's one of the few true intellectuals to be so dismissive of the global-warming consensus

From: Steve Connor

To: Freeman Dyson

You are one of the most famous living scientists, credited as a visionary who has reshaped scientific thinking. Some have called you the "heir to Einstein", yet you are also a "climate sceptic" who questions the consensus on global warming and its link with carbon dioxide emissions. Could we start by finding where we agree? I take it you accept for instance that carbon dioxide is a powerful greenhouse gas that warms the planet (1); that atmospheric concentrations of CO2 have risen since direct measurements began several decades ago (2); and that CO2 is almost certainly higher now than for at least the past 800,000 years (3), if you take longer records into account, such as ice-core data.

Would you also accept that CO2 levels have been increasing as a result of burning fossil fuels and that global temperatures have been rising for the past 50 years at least, and possibly for longer (4)? Computer models have shown that the increase in global temperatures can only be explained by the increase in atmospheric CO2 concentrations (5). Climate scientists say there is no other reasonable explanation for the warming they insist is happening (6), which is why we need to consider doing something about it (7). What part of this do you accept and what do you reject?

From: Freeman Dyson

To: Steve Connor

First of all, please cut out the mention of Einstein. To compare me to Einstein is silly and annoying.

There are six good reasons for saying no to the last three assertions. First, the computer models are very good at solving the equations of fluid dynamics but very bad at describing the real world. The real world is full of things like clouds and vegetation and soil and dust which the models describe very poorly. Second, we do not know whether the recent changes in climate are on balance doing more harm than good. The strongest warming is in cold places like Greenland. More people die from cold in winter than die from heat in summer. Third, there are many other causes of climate change besides human activities, as we know from studying the past. Fourth, the carbon dioxide in the atmosphere is strongly coupled with other carbon reservoirs in the biosphere, vegetation and top-soil, which are as large or larger. It is misleading to consider only the atmosphere and ocean, as the climate models do, and ignore the other reservoirs. Fifth, the biological effects of CO2 in the atmosphere are beneficial, both to food crops and to natural vegetation. The biological effects are better known and probably more important than the climatic effects. Sixth, summing up the other five reasons, the climate of the earth is an immensely complicated system and nobody is close to understanding it.

Princeton physicist Freeman Dyson has been roundly criticized for insisting global warming is not an urgent problem, with many climate scientists dismissing him as woefully ill-informed. In an interview with Yale Environment 360, Dyson explains his iconoclastic views and why he believes they have stirred such controversy.